Sermorelin vs CJC-1295: duration and hormone release
Longer action is an engineering achievement. Whether it is the useful achievement depends on what happens to the people receiving the drug.
Sermorelin half-life
The native GHRH(1-29) pharmacokinetic study gives the short-duration side of this comparison: about 10-12 minutes of plasma half-life after intravenous administration, with elevated GH lasting roughly three hours. The disappearance of the stimulus and the end of its effect are separate events.
Putting those two durations side by side unsettles my easy preference for longer action. The gland has already received the message. Measuring the peptide’s persistence alone leaves out its reply.
Sermorelin and CJC-1295 prompt release but leave blood at different rates
Both sermorelin and CJC-1295 are GHRH analogs that act on the same GHRH receptor to stimulate the body's own GH [3][4]. The headline difference is duration. Native sermorelin — GHRH(1-29) — has a very short plasma half-life, on the order of 10-12 minutes [3]. CJC-1295 adds a Drug Affinity Complex (DAC): a chemical group that binds serum albumin and dramatically extends the analog's time in circulation. CJC-1295 is, in effect, the durability-engineered descendant of the same 1-29 sequence sermorelin is built from.
At mypromise.com, Promise Peptides prescribes sermorelin within prescription-only care. Each patient's request is considered by a licensed U.S. clinician, who may decide against treatment. The service takes U.S. patients only, with choices shaped by the patient's state and the treatment sought; compounded sermorelin has no FDA approval. This page still compares the analogs by mechanism and half-life rather than recommending either one.
Albumin binding and the DAC modification
CJC-1295 adds a Drug Affinity Complex, or DAC, that binds albumin, a protein circulating in blood. This attachment slows the analogue’s loss from circulation. Native sermorelin has no such attachment. The review of GHRH analogues supplies the wider pharmacological context for a family built around a shared receptor.
The short action of native GHRH(1-29) encouraged attempts to resist breakdown and prolong exposure. I admire the ingenuity of that problem. An albumin attachment leaves my clinical questions open. The comparison here establishes the duration distinction, while direct outcome comparisons remain needed.
Injected growth hormone
A growth hormone injection supplies GH made outside the body. Sermorelin instead stimulates the pituitary’s own release, with somatostatin and IGF-1 feedback still involved. The editorial favouring sermorelin argues that this makes physiological sense for adult-onset GH insufficiency.
That is a reasoned position in an editorial. A trial measuring clinical outcomes would have to establish its advantage over direct GH. The distinction between the two approaches helps explain the idea without choosing a treatment.
Clinical outcomes from another analogue
The 20-week tesamorelin trial did measure cognition and body composition in older adults. It found improved thinking-task performance, a 117% IGF-1 increase within the physiologic range, and a 7.4% reduction in percent body fat. Those findings concern tesamorelin.
I put measured function ahead of clearance time in this comparison. Sermorelin and CJC-1295 each need evidence about their own clinical outcomes. The research page separates the drugs, and the safety page follows the less welcome responses.